remoting: Cleanup class/struct fwd declarations

remoting/protocol/connection_to_host.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef REMOTING_PROTOCOL_CONNECTION_TO_HOST_H_
 #define REMOTING_PROTOCOL_CONNECTION_TO_HOST_H_
 
 #include <memory>
 #include <string>
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "remoting/protocol/errors.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace remoting {
 namespace protocol {
 
 class AudioStub;
-class Authenticator;
 class ClientStub;
 class ClipboardStub;
 class HostStub;
 class InputStub;
 class Session;
 class SessionConfig;
 class TransportContext;
 struct TransportRoute;
 class VideoRenderer;
 
@@ skipping 66 matching lines @@
   virtual InputStub* input_stub() = 0;
 
   // Return the current state of ConnectionToHost.
   virtual State state() const = 0;
 };
 
 }  // namespace protocol
 }  // namespace remoting
 
 #endif  // REMOTING_PROTOCOL_CONNECTION_TO_HOST_H_